Mercedes-Benz A-Class LWB - ex police road tax - nelly741

can anyone pass info regarding the ex police car tax, i have just purchased a vehicle where the dealer told me i was taxed and i drove from london to wigan then read this forum to find out that he was filling me with cr.p.I would like to know what proceedure i have to follow to get the vehicle taxed ,can someone advise me please,i have the logbook , the cover note ,bill of sale,and a knackered megane waiting to die .the sooner the better . thanks for reading neill

Mercedes-Benz A-Class LWB - ex police road tax - TR7
You need to got to your nearest dvla office.